The present disclosure generally relates to a rock crushing machine, such as a rock crusher of configurations commonly referred to as gyratory or cone crushers. More specifically, the present disclosure relates to a suspension system for adjustably supporting an upper end of a mainshaft of the gyratory crusher within a stationary spider hub of the gyratory crusher.
Rock crushing machines break apart rock, stone or other materials in a crushing cavity formed between a downwardly expanding conical mantle installed on a mainshaft that gyrates within an outer upwardly expanding frustoconically shaped assembly of concaves inside a crusher shell assembly. The conical mantle and the mainshaft are circularly symmetric about an axis that is inclined with respect to the vertical shell assembly axis. These axes intersect near the top of the rock crusher. The inclined axis is driven circularly about the vertical axis thereby imparting a gyrational motion to the mainshaft and mantle. The gyrational motion causes points on the mantle surface to alternately advance toward and retreat away from the stationary concaves. During retreat of the mantle, material to be crushed falls deeper into the cavity where it is crushed when motion reverses and the mantle advances toward the concaves.
A spider is attached to the upper edge of the crusher shell assembly, forming the top of a support structure for the mainshaft. The material to be crushed is typically dropped into the shell assembly and past abrasion resistant spider arm shields that are positioned over radially extending spider arms that are each joined to a central spider hub. After either passing by or contacting the spider arms or the spider hub, the material to be crushed falls into the crushing cavity. In currently available gyratory crushers, the spider hub includes a bushing that receives one end of the gyrating mainshaft.
During the extended use of the gyratory crusher, the liners formed on a stationary bowl begin to wear, which changes the size of the crushing gap. In order to compensate for this wear, the vertical position of the mainshaft assembly is adjusted, which allows the discharge setting of the crusher to remain constant.
Presently, the different styles of gyratory crushers either have a mainshaft supported at the bottom by a large hydraulic cylinder, which allows for adjustment of the shaft position from below the crusher, or a mechanical threaded suspension at the top of the mainshaft. Gyratory crushers with bottom supported suspension systems are difficult to maintain since the adjustment cylinder assembly is large and heavy and the discharge chamber under the crusher must be cleaned out before access to the adjustment mechanism is possible.
Top threaded suspension systems also require a difficult and time-consuming process in order to adjust the vertical position of the mainshaft. This adjustment process typically includes having to lift a very heavy mainshaft with an overhead crane to unload a split adjustment nut so that the adjustment nut can be manually threaded down further on the mainshaft threads, which would then raise the mainshaft vertical position.
In addition, gyratory crushers that feature hydraulic supported suspension systems for the mainshaft, such as in the Metso MK-II or the Nordberg XP50 gyratory crushers, suffer from additional problems when used to crush material with very hard ore properties. When a piece of such very hard material enters the crushing gap, the material can create a crushing force that forces the mainshaft upward, causing the mainshaft to jump, which is an undesirable condition. In addition, previously available hydraulic top suspension systems also typically include a moving pivot point between the mainshaft and the stationary bearings, which can become misaligned during use and adjustment.
Based upon the limitations associated with these two currently available adjustment systems for the mainshaft of a gyratory crusher, a need exists for an improved adjustment system that allows the vertical position to be more easily adjusted.